From 2b41fab70fc001d2acd89c0477d32feb8265bb32 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 22 Mar 2015 10:22:18 -0700 Subject: [PATCH] inet: cache listen_sock_qlen() and read rskq_defer_accept once Cache listen_sock_qlen() to limit false sharing, and read rskq_defer_accept once as it might change under us. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/inet_connection_sock.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 844808d9337b..7d011e825c48 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -571,8 +571,9 @@ static void reqsk_timer_handler(unsigned long data) struct inet_connection_sock *icsk = inet_csk(sk_listener); struct request_sock_queue *queue = &icsk->icsk_accept_queue; struct listen_sock *lopt = queue->listen_opt; - int expire = 0, resend = 0; + int qlen, expire = 0, resend = 0; int max_retries, thresh; + u8 defer_accept; if (sk_listener->sk_state != TCP_LISTEN || !lopt) { reqsk_put(req); @@ -598,19 +599,21 @@ static void reqsk_timer_handler(unsigned long data) * embrions; and abort old ones without pity, if old * ones are about to clog our table. */ - if (listen_sock_qlen(lopt) >> (lopt->max_qlen_log - 1)) { + qlen = listen_sock_qlen(lopt); + if (qlen >> (lopt->max_qlen_log - 1)) { int young = listen_sock_young(lopt) << 1; while (thresh > 2) { - if (listen_sock_qlen(lopt) < young) + if (qlen < young) break; thresh--; young <<= 1; } } - if (queue->rskq_defer_accept) - max_retries = queue->rskq_defer_accept; - syn_ack_recalc(req, thresh, max_retries, queue->rskq_defer_accept, + defer_accept = READ_ONCE(queue->rskq_defer_accept); + if (defer_accept) + max_retries = defer_accept; + syn_ack_recalc(req, thresh, max_retries, defer_accept, &expire, &resend); req->rsk_ops->syn_ack_timeout(sk_listener, req); if (!expire && -- 2.30.2